1. Field of the Invention
The present invention relates to optical switches used to connect optical fibers at a central office to a source of optical fiber test signals. More particularly, the present invention relates to an optical switch system that selectively directs optical test signals to optical fibers that are part of a fiber administration system.
2. Description of the Prior Art
There are many applications that utilize an optical fiber network to establish optical communications between a host digital terminal (HDT) at a central office and an optical network unit (ONU) at a remote location. Since a central office serves as the point of origin for the optical fibers in the optical fiber network, fiber administration systems are typically used at the central office to manage the flow of optical signals as they are directed to the various ONUs along the different optical fibers in the network.
In many fiber administration systems, as the optical fibers in a network enter the central office, they are directed into an optical distribution frame where the individual optical fibers are terminated in an organized manner. Such fiber administration systems are exemplified by the LGX.RTM. fiber administration system which is currently manufactured by Lucent Technologies of Murray Hill, N.J., the assignee herein. In such fiber administration systems, the optical distribution frames used at the central office are typically large structures that are arranged in parallel rows. Each optical distribution frame is commonly mounted between the floor and ceiling and only a few feet separate each row of frames.
Each optical distribution frame located at the central office typically defines a plurality of bays, wherein each bay houses several fiber distribution shelves. On each of the fiber distribution shelves are connection modules that receive the ends of all of the individual optical fibers that enter the central office and are contained within the optical fiber network. By terminating each optical fiber at a connection module on one of the different fiber distribution shelves, the location of each optical fiber becomes known within the overall assembly. Once terminated at a known address on one of the fiber distribution shelves, each optical fiber can be selectively coupled to a HDT or a variety of other optical equipment located at the central office. As a result, the optical signals sent along each optical fiber can be selectively controlled.
When an optical fiber cable is newly laid, repaired, sliced or otherwise altered, it is important to check the optical integrity in between the central office and each ONU. As a result, each time an optical fiber cable is altered, the integrity of the overall optical pathway must be tested. In many applications, an optical cable exiting the central office contains several different optical ribbons. Each of the ribbons contains a plurality of individual optical fibers. When an optical cable is spliced, the cable is cut open and each of the optical ribbons contained within that cable are spliced individually. As such, when one optical ribbon is spliced to another, several different individual optical fibers are being spliced during that operation. If any one of the optical fibers in the optical ribbon fails to splice properly, either that ribbon or the entire optical cable must be cut and re-spliced.
After all of the splices have been made between the central office and an ONU, the overall optical path is tested. In these tests, testing equipment is connected to the optical fibers in the pathway both at the central office and at the remote location. Typically a first test signal is sent from the central office to the remote location. A second test signal is then generated at the remote location and sent to the central office. Through analysis of both test signals the integrity and transmission characteristics of the optical pathway can be quantified.
Often when testing an optical pathway, different tests need to be performed. These tests may be performed by different pieces of test equipment. Else, such tests may be performed by utilizing different test signals from the same piece of testing equipment. At both the central office and the remote location there is only one terminated connector that leads to each of the optical fibers in the optical pathway. As a result, only one piece of testing equipment can be connected to each end of an optical fiber at any one time. Accordingly, only one test signal can be introduced into each optical fiber at either end. To change the test signal, the test equipment must be changed or reset. The secondary tests must then be performed after the primary tests. This adds significantly to the overall time and labor needed to complete a full series of tests on an optical pathway.
A need therefore exists in the art for an optical switch assembly that can be coupled to a plurality of different pieces of test equipment and can run tests from the different pieces of testing equipment simultaneously.